As the state of development of semiconductor components has moved to increased levels of integration, the amount of heat these devices generate has significantly increased. Components handling large quantities of current such as power transistors and integrated circuits generate large amounts of heat. For instance, as indicated in U.S. Pat. No. 5,598,320, it is commonly known that the current generation of P5 microprocessor chips, such as Intel Corporation's Pentium.RTM. Pro microprocessor, generate a significant amount of heat during operation. If this heat is not adequately removed, the increased temperatures generated by the semiconductor components will damage the components. As the computer industry moves toward ever increasing integration of these components, this will continue to be a common problem for the industry.
One approach for solving the heat dissipation problem is to include components which transfer or dissipate heat by means of heat sinks, including heat dissipation plates, fin stacks, and heat pipes. These devices keep the microprocessor chip and related circuitry below the maximum recommended operating temperature by transferring or dissipating heat away from the chip and related circuitry.
A typical heat sink component dissipates heat from a semiconductor component by maintaining thermal contact with the component. The thermal contact area is maximized for the efficient dissipation of heat. A heat sink includes a plate made up of conductive metal and a thermal interface to optimize the heat transfer from the semiconductor component. The heat sink transfers heat from the semiconductor component to less heat-sensitive locations. A typical heat sink maintains thermal contact between the thermal conducting plate and the semiconductor component to dissipate heat in an efficient manner.
A typical heat sink includes a plurality of protrusions, called fins, that increase the overall surface area of the heat sink which increases the heat dissipation capacity, resulting in a more efficient heat transfer system. A fin assembly can be comprised of plate-like radiating fins or pin-like radiating fins and protrudes from a heat sink body for efficient heat dissipation. Increasing the heat dissipating surface area improves the heat dissipating efficiency of the heat sink component. Fin stacks can be particularly effective at dissipating heat due to the increased surface area. The enlarged surface area created by the fins dissipates the heat generated by the semiconductor components more efficiently than a heat sink thermal plate alone.
Heat pipes are another effective method of transferring heat from the critical area of the semiconductor components and related circuitry to the heat fins. As discussed in U.S. Pat. No. 5,598,320, the heat pipe generally improves the heat dissipation features of a heat sink by carrying heat from the microprocessor component and related circuitry to an area where there is sufficient air flow to effectively dissipate heat.
A heat pipe is situated in thermal contact with a semiconductor component such that heat is transferred from the area surrounding the semiconductor component to the fin stack. A heat pipe may be a hollow tube that is filled, in part, with a fluid such as water. As discussed in U.S. Pat. No. 4,675,783, heat pipes have been found generally to cool more efficiently than heat sinks with heat dissipating plates. Recently, more computer vendors have combined heat sink and heat pipe solutions to increase efficiency for overall heat dissipation in semiconductor devices.
There is continuing pressure to lower the cost of computer systems. This, coupled with the increase in semiconductor component integration have created a need to provide for the control of a variety of thermal conditions in a low cost package.
A power converter converts one form of energy to another. As discussed in U.S. Pat. No. 5,621,635, heat sinks have been attached to the outside of a printed circuit board containing a power converter, to aid in heat dissipation. Some of the problems addressed by past power converter and heat sink technologies include: the large amount of space required on the circuit board; the general inefficiency of heat dissipation when large numbers of thermal interfaces are used; the cost of manufacturing which can be high if ceramic substrate or thermally enhanced boards are used; and the difficulty in maintaining high degrees of reliability. One typical solution to the problem of minimizing heat dissipation from a power converter is to ensure that intimate physical contact between a power converter and a heat sink is achieved.
Another packaging problem in the industry is containing electromagnetic (EMI) or radio frequency (RFI) disturbances generated by semiconductor components. Hereinafter EMI and RFI disturbances will be referred to as "EMI". A Faraday Cage solution to the EMI problem is an enclosure which attenuates EMI emission. It is designed to effectively shield EMI disturbances while permitting air flow for dissipation of heat. As discussed in U.S. Pat. No. 5,398,822, EMI is contained by enclosing the area surrounding semiconductor modules in order to prevent EMI discharge. This works in counterbalance to the need to open up the areas surrounding semiconductor modules for the dissipation of heat. EMI enclosures often are made of sheet metal with a plurality of small holes for ventilation. EMI enclosures are often coupled with the use of fans to move air through the small ventilation holes to accelerate heat dissipation.
The problem with the past technology is that semiconductor modules and power converter modules generate significant heat which must be efficiently dissipated. They also generate EMI which must be shielded. This has led to difficulties in designing inexpensive packaging of semiconductor modules in which heat dissipance and EMI reduction are efficiently controlled.